Many techniques are employed to generate imaged information on surfaces. For example, pens, ink jet printers, lithographic printers, flexographic printers, and the like have been used to apply information to a substrate. One problem that has been encountered with these techniques is the tendency of the marking fluids, such as inks or other liquids which are used to "wick" or spread out on or in the substrate. The resultant images then are neither well defined nor aesthetically pleasing.
Attempts to overcome the problem of wicking or spreading have included the bulk application of materials which retard or prevent these phenomena. However, such bulk application suffers the disadvantage that it hinders penetration of the marking fluid into the printed surface. This in turn hinders drying of the ink and increases the chance that offsetting will occur when the marked sheets are stacked on one another. When a transparentizing fluid is employed, such bulk application blocks penetration of the marking fluid into the surface and prevents making the mark visible.
Examples of the use of transparentizing fluids are discussed in a number of patents. For example, U.S. Pat. No. 4,877,253, (Arens) discloses a sheet material which can be temporarily transparentized (thereby marked) by the use of a colorless volatile liquid. A liquid impervious support can be used to prevent the volatile liquid from leaking out of the back of the sheets.
U.S. Pat. No. 4,418,098, (Maistrovich) discloses a microvoid sheet which can be transparentized by applying a colorless liquid which is a non-solvent for the microvoid network. The colorless liquid is jellified by a slightly soluble polymeric material which is applied to the entire sheet and occupies about 5% of the void volume.
U.S. Pat. No. 4,374,889, (Arens) discloses a microvoid sheet which is transparentized by application of liquids having surface tensions lower than about 30 dynes. This is accomplished by treating the entire area of one side of the sheet with oleophobic and hydrophobic substances. The other side of the sheet is left untreated.
There still exists a need for an article which can accept a marking fluid and provide a well defined image thereon.